Methods and apparatuses for treating the spine through an access device

ABSTRACT

In a method of treating the spine of a patient, a fusion device is implanted via an anterior approach in an interbody space between at least two of a first vertebra, a second vertebra and a third vertebra. An access device is inserted into the patient with the access device in a first configuration having a first cross-sectional area at a distal portion thereof. The access device is actuated to a second configuration having an enlarged cross-sectional area at the distal portion thereof such that the distal portion extends across at least a portion of each of the three adjacent vertebrae. A multi-level procedure is performed through the access device across the at least three adjacent vertebrae.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. applicationSer. No. 10/280,489, filed Oct. 25, 2002, which is incorporated byreference hereinbelow in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to methods and apparatuses for performingminimally invasive surgery, and more particularly to instruments forproviding access to body tissues and performing procedures on bonestructures of a patient.

[0004] 2. Description of the Related Art

[0005] Spinal surgery presents significant difficulties to the physicianattempting to reduce chronic back pain or correct spinal deformitieswithout introducing additional trauma due to the surgical procedureitself. In order to access the vertebrae to perform spinal procedures,the physician is typically required to make large incisions and cut orstrip muscle tissue surrounding the spine. In addition, care must betaken not to injure nerve tissue in the area. Consequently, traditionalsurgical procedures of this type carry high risks of scarring, pain,significant blood loss, and extended recovery times.

[0006] Apparatuses for performing minimally invasive techniques havebeen proposed to reduce the trauma of posterior spinal surgery byreducing the size of the incision and the degree of muscle stripping inorder to access the vertebrae. One such apparatus provides a constantdiameter cannula which is made narrow in order to provide a small entryprofile. As a result, the cannula provides minimal space for thephysician to observe the body structures and manipulate surgicalinstruments in order to perform the required procedures. A narrowcannula is typically insufficient to perform one level spinal fixationprocedures, which requires visualization of two vertebrae andintroduction of screws, rods, as well as other large spinal fixationdevices.

[0007] In some cases it is desirable to provide treatment of more thantwo adjacent vertebrae. For example, some conditions require thattreatment be made of three adjacent vertebrae, i.e., a “two levelprocedure.” While a narrow constant diameter cannula is typicallyinsufficient for a one level procedure, such a cannula is completelyinadequate for a two level procedure. Thus a variety of procedures andcombination of procedures requires repeated insertion of multiplecannulae, which eliminates the advantages of minimally invasiveprocedures.

SUMMARY OF THE INVENTION

[0008] Accordingly, there is a need in the art for systems and methodsfor treating the spine which provide minimally invasive access to thespine such that a variety of procedures, and preferably the entireprocedure, can be performed via a single access device.

[0009] In one embodiment, a method of treating a spine of a patient isprovided. A fusion device is implanted via an anterior approach in aninterbody space between at least two of a first vertebra, a secondvertebra and a third vertebra. An access device is inserted into thepatient with the access device in a first configuration having a firstcross-sectional area at a distal portion thereof. The access device isactuated to a second configuration having an enlarged cross-sectionalarea at the distal portion thereof such that the distal portion extendsacross at least a portion of each of the three adjacent vertebrae. Amulti-level procedure is performed through the access device across theat least three adjacent vertebrae.

[0010] In one embodiment, a method of treating a spine of a patient isprovided. An interbody space between at least two of a first vertebra, asecond vertebra, and a third vertebra is exposed anteriorly. A fusiondevice is placed in the interbody space. An access device is insertedthrough an incision in the skin of the patient generally posteriorlyuntil a distal portion thereof is located adjacent the spine. The accessdevice is inserted in a first configuration. The first configuration hasa first cross-sectional area at a distal portion thereof. The accessdevice is actuated to a second configuration. The second configurationhas an enlarged cross-sectional area at the distal portion thereof. Afirst fastener configured for insertion into the patient through theaccess device and for attachment to the first vertebra is provided. Asecond fastener configured for insertion into the patient through theaccess device and for attachment to a second vertebra is provided. Athird fastener configured for insertion into the internal passage of theexpandable conduit and for attachment to a third vertebra is provided.The first, second, and third fasteners are attached to the first,second, and third vertebrae. An elongated member is inserted through theaccess device and is moved adjacent to the first, second, and thirdfasteners. The elongate member is secured to the first, second, andthird fasteners.

[0011] In another embodiment, a method of treating a spine of a patientis provided. An interbody space between at least two of a firstvertebra, a second vertebra, and a third vertebra is exposed anteriorly.A fusion device is placed in the interbody space. An access device isinserted through an incision in the skin of the patient generallyposteriorly until a distal portion thereof is located adjacent thespine. The access device is inserted in a first configuration. The firstconfiguration has a first cross-sectional area at a distal portionthereof. The access device is actuated to a second configuration thathas an enlarged cross-sectional area at the distal portion thereof. Adecompression tool is advanced through the access device. A portion ofbone is removed from at least one of the first, second, and the thirdvertebrae through the access device. A first fastener configured forinsertion into the patient through the access device and for attachmentto the first vertebra is provided. A second fastener configured forinsertion into the patient through the access device and for attachmentto a second vertebra is provided. A third fastener configured forinsertion into the internal passage of the expandable conduit and forattachment to a third vertebra is provided. The first, second, and thirdfasteners are attached to the first, second, and third vertebrae. Anelongated member is inserted through the access device and is movedadjacent to the first, second, and third fasteners. The elongate memberis secured to the first, second, and third fasteners.

[0012] In another embodiment, a method of treating a spine of a patientis provided. An interbody space between at least two of a firstvertebra, a second vertebra, and a third vertebra is exposed. A fusiondevice is placed in the interbody space. An access device is insertedthrough an incision in the skin of the patient generally posteriorlyuntil a distal portion thereof is located adjacent the spine. The accessdevice is inserted in a first configuration having a firstcross-sectional area at a distal portion thereof. The access device isactuated to a second configuration having an enlarged cross-sectionalarea at the distal portion thereof. A first fastener configured forinsertion into the patient through the access device and for attachmentto the first vertebra is provided. A second fastener configured forinsertion into the patient through the access device and for attachmentto a second vertebra is provided. A third fastener configured forinsertion into the internal passage of the expandable conduit and forattachment to a third vertebra is provided. The first, second, and thirdfasteners are attached to the first, second, and third vertebrae. Anelongated member is inserted through the access device and is movedadjacent to the first, second, and third fasteners. The elongate memberis secured to the first, second, and third fasteners. A bone growthsubstance is placed through the access device and adjacent at least oneof the first, second, and third fasteners and the elongate member toenhance bone growth.

[0013] In another embodiment, a method of treating a spine of a patientis provided. An interbody space between at least two of a firstvertebra, a second vertebra, and a third vertebra is exposed anteriorly.A fusion device is placed in the interbody space. An access device isinserted through an incision in the skin of the patient generallyposteriorly until a distal portion thereof is located adjacent thespine. The access device is inserted in a first configuration having afirst cross-sectional area at a distal portion thereof. The accessdevice is actuated to a second configuration having an enlargedcross-sectional area at the distal portion thereof. A bone growthsubstance is placed through the access device and adjacent an interbodyspace defined between at least two of the first, second, and thirdvertebrae to enhance bone growth therebetween.

[0014] In another embodiment, another method of treating a spine of apatient is provided. An access device is through an incision in the skinof the patient generally posteriorly until a distal portion thereof islocated adjacent the spine. The access device is inserted in a firstconfiguration having a first cross-sectional area at a distal portionthereof. The access device is actuated to a second configuration thathas an enlarged cross-sectional area at the distal portion thereof. Theenlarged configuration spans at least a portion of a first vertebra, asecond vertebra, and a third vertebra. A fusion device is placed throughthe access device and in at least one of a first interbody space betweenthe first and second vertebrae and a second interbody space between thesecond and third vertebrae. A bone growth substance is placed throughthe access device and adjacent at least one of the first interbody spaceand the second interbody space to enhance bone growth therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further objects, features and advantages of the invention willbecome apparent from the following detailed description taken inconjunction with the accompanying figures showing illustrativeembodiments of the invention, in which:

[0016]FIG. 1 is a perspective view of one embodiment of a surgicalsystem and one embodiment of a method for treating the spine of apatient;

[0017]FIG. 2 is a perspective view of one embodiment of an expandableconduit in a reduced profile configuration;

[0018]FIG. 3 is a perspective view of the expandable conduit of FIG. 2in a first enlarged configuration;

[0019]FIG. 4 is a perspective view of the expandable conduit of FIG. 2in a second enlarged configuration;

[0020]FIG. 5 is a view of one embodiment of a skirt portion of anexpandable conduit;

[0021]FIG. 6 is a view of another embodiment of a skirt portion of anexpandable conduit;

[0022]FIG. 7 is a perspective view of another embodiment of anexpandable conduit in an enlarged configuration;

[0023]FIG. 8 is an enlarged sectional view of the expandable conduit ofFIG. 7 taken along lines 8-8 of FIG. 7;

[0024]FIG. 9 is a sectional view of the expandable conduit of FIG. 7taken along lines 9-9 of FIG. 7;

[0025]FIG. 10 is a perspective view of another embodiment of anexpandable conduit in an enlarged configuration;

[0026]FIG. 11 is an enlarged sectional view of the expandable conduit ofFIG. 10 taken along lines 11-11 of FIG. 10;

[0027]FIG. 12 is a sectional view of the expandable conduit of FIG. 10taken along lines 12-12 of FIG. 10;

[0028]FIG. 13 is a view of a portion of another embodiment of theexpandable conduit;

[0029]FIG. 14 is a view of a portion of another embodiment of theexpandable conduit;

[0030]FIG. 15 is a sectional view illustrating one embodiment of a stageof one embodiment of a method for treating the spine of a patient;

[0031]FIG. 16 is a side view of one embodiment of an expander apparatusin a reduced profile configuration;

[0032]FIG. 17 is a side view of the expander apparatus of FIG. 16 in anexpanded configuration;

[0033]FIG. 18 is a sectional view of the expander apparatus of FIGS.16-17 inserted into the expandable conduit of FIG. 2, which has beeninserted into a patient;

[0034]FIG. 19 is a sectional view of the expander apparatus of FIGS.16-17 inserted into the expandable conduit of FIG. 2 and expanded to theexpanded configuration to retract tissue;

[0035]FIG. 20 is an exploded perspective view of one embodiment of anendoscope mount platform;

[0036]FIG. 21 is a top view of the endoscope mount platform of FIG. 20coupled with one embodiment of an indexing arm and one embodiment of anendoscope;

[0037]FIG. 22 is a side view of the endoscope mount platform of FIG. 20illustrated with one embodiment of an indexing arm and one embodiment ofan endoscope;

[0038]FIG. 23 is a perspective view of one embodiment of an indexingcollar of the endoscope mount platform FIG. 20;

[0039]FIG. 24 is a perspective view of one embodiment of an endoscope;

[0040]FIG. 25 is a partial sectional view of one embodiment of a stageof one embodiment of a method for treating the spine of a patient;

[0041]FIG. 26 is a perspective view of one embodiment of a fastener;

[0042]FIG. 27 is an exploded perspective view of the fastener of FIG.26;

[0043]FIG. 27(a) is an enlarged side view of one embodiment of a biasingmember illustrated in FIG. 27 taken from the perspective of the arrow 27a;

[0044]FIG. 28 is a perspective view of one embodiment of a surgicalinstrument;

[0045]FIG. 29 is an enlarged sectional view of the fastener of FIGS.26-27 coupled with the surgical instrument of FIG. 28, illustrating oneembodiment of a stage of one embodiment of a method for treating thespine of a patient;

[0046]FIG. 30 is side view of one embodiment of another surgicalinstrument;

[0047]FIG. 31 is a partial sectional view of one embodiment of a stageof one embodiment of a method for treating the spine of a patient;

[0048]FIG. 32 is a side view of one embodiment of another surgicalinstrument;

[0049]FIG. 33 is a perspective view similar to FIG. 31 illustrating theapparatuses of FIGS. 26 and 32, in one embodiment of a stage of oneembodiment of a method for treating the spine of a patient;

[0050]FIG. 34 is an enlarged sectional view of the apparatus of FIGS. 26and 32, illustrating one embodiment of a stage of one embodiment of amethod for treating the spine of a patient;

[0051]FIG. 35 is an enlarged sectional similar to FIG. 34, illustratingone embodiment of a stage of one embodiment of a method for treating thespine of a patient;

[0052]FIG. 36 is an enlarged view in partial section illustrating oneembodiment of a stage of one embodiment of a method for treating thespine of a patient; and

[0053]FIG. 37 is a partial view of illustrating one embodiment of astage of one embodiment of a method for treating the spine of a patient.

[0054] Throughout the figures, the same reference numerals andcharacters, unless otherwise stated, are used to denote like features,elements, components or portions of the illustrated embodiments.Moreover, while the subject invention will now be described in detailwith reference to the figures, it is done so in connection with theillustrative embodiments. It is intended that changes and modificationscan be made to the described embodiments without departing from the truescope and spirit of the subject invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0055] As should be understood in view of the following detaileddescription, this application is directed to apparatuses and methods fortreating the spine of a patient through an access device, also referredto herein as an expandable conduit. More particularly, the systemsdescribed below provide access to surgical locations at or near thespine and provide a variety of tools useful in performing treatment ofthe spine. Also, the systems described herein enable a surgeon toperform a wide variety of methods as described herein.

I. Systems for Performing Procedures at a Surgical Location

[0056] Various embodiments of apparatuses and procedures describedherein will be discussed in terms minimally invasive procedures andapparatuses, e.g., of endoscopic apparatuses and procedures. However,many aspects of the present invention may find use in conventional,open, and mini-open procedures. In the drawings and description whichfollows, the term “proximal,” as is traditional, refers to the endportion of the apparatus which is closest to the operator, while theterm “distal” will refer to the end portion which is farthest from theoperator.

[0057]FIG. 1 shows one embodiment of a surgical system 10 that can beused to perform a variety of methods or procedures. In at least aportion of the procedure, as discussed more fully below, the patient Ptypically is placed in the prone position on operating table T, takingcare that the abdomen is not compressed and physiological lordosis ispreserved, as is known in the art. The physician D is able to access thesurgical site and perform the surgical procedure with the components ofthe system 10, which will be described in greater detail herein. Thesystem 10 may be supported, in part, by a mechanical support arm A, suchas the type generally disclosed in U.S. Pat. No. 4,863,133, which ishereby incorporated by reference herein in its entirety. One mechanicalarm of this type is manufactured by Leonard Medical, Inc., 1464 HolcombRoad, Huntington Valley, Pa., 19006.

[0058] Visualization of the surgical site may be achieved in anysuitable manner, e.g., by use of a viewing element, such as anendoscope, a camera, loupes, a microscope, direct visualization, or anyother suitable viewing element, or a combination of the foregoing. Inone embodiment, the viewing element provides a video signal representingimages, such as images of the surgical site, to a monitor M. The viewingelement may be an endoscope and camera which captures images to bedisplayed on the monitor M whereby the physician D is able to view thesurgical site as the procedure is being performed. The endoscope andcamera will be described in greater detail herein.

[0059] The systems and procedures will be described herein in connectionwith minimally invasive postero-lateral spinal surgery. One such methodis a two level postero-lateral fixation of the spine involving the L4,L5, and S1 vertebrae. (In the drawings, the vertebrae will generally bedenoted by reference letter V.) The usefulness of the apparatuses andprocedures is neither restricted to the postero-lateral approach nor tothe L4, L5, and S1 vertebrae, but it may be used in other anatomicalapproaches and other vertebra(e) within the cervical, thoracic, andlumbar regions of the spine. The procedures may be directed towardsurgery involving one or more vertebral levels. It is also useful foranterior and lateral procedures. Moreover, it is believed that theinvention is also particularly useful where any body structures must beaccessed beneath the skin and muscle tissue of the patient, and where itdesirable to provide sufficient space and visibility in order tomanipulate surgical instruments and treat the underlying bodystructures. For example, certain features or instrumentation describedherein are particularly useful for a minimally invasive procedures,e.g., arthroscopic procedures. As discussed more fully below, oneembodiment of an apparatus described herein provides an expandableconduit that has an expandable distal portion. The expandable distalportion prevents or substantially prevents the expandable conduit orinstruments extended therethrough to the surgical site from beingdislodging or popping out of the operative site.

[0060] The system 10 includes an expandable conduit or access devicethat provides a internal passage for surgical instruments to be insertedthrough the skin and muscle tissue of the patient P to the surgicalsite. The expandable conduit has a wall portion defining reduced profileconfiguration for initial percutaneous insertion into the patient. Thiswall portion may have any suitable arrangement. In one embodiment,discussed in more detail below, the wall portion has a generally tubularconfiguration that may be passed over a dilator that has been insertedinto the patient to atraumatically enlarge an opening sufficiently largeto receive the expandable conduit therein.

[0061] The wall portion of the expandable conduit is subsequentlyexpanded to an enlarged configuration, by moving against the surroundingmuscle tissue to at least partially define an enlarged surgical space inwhich the surgical procedures will be performed. In a sense, it acts asits own dilator. The expandable conduit may also be thought of as aretractor, and may be referred to herein as such. Typically, but not byway of limitation, the distal portion expands to a greater extent thanthe proximal portion, because the surgical procedures are to beperformed at the surgical site which is adjacent the distal portion whenthe expandable conduit is inserted into the patient.

[0062] While in the reduced profile configuration, the expandableconduit defines a first unexpanded configuration. Thereafter, theexpandable conduit enlarges the surgical space defined thereby byengaging the tissue surrounding the conduit and displacing the tissueradially outwardly as the conduit expands. The expandable conduit may besufficiently rigid to displace such tissue during the expansion thereof.The expandable conduit may be resiliently biased to expand from thereduced profile configuration to the enlarged configuration. Inaddition, the conduit may also be manually expanded by an expanderdevice with or without one or more surgical instruments insertedtherein, as will be described below. The surgical site is at leastpartially defined by the expanded conduit itself. During expansion, theconduit moves from the first overlapping configuration to a secondoverlapping configuration.

[0063] In addition to enlargement, the distal end portion of theexpandable conduit may be configured for relative movement with respectto the proximal end portion in order to allow the physician to preciselyposition the distal end portion at the desired location. This relativemovement also provides the advantage that the proximal portion of theexpandable conduit nearest the physician D may remain substantiallystable during such distal movement. In an exemplary embodiment, thedistal portion is a separate component which is pivotably or movablyattached relative to the proximal portion. In another embodiment, thedistal portion is flexible or resilient in order to permit such relativemovement.

[0064] One embodiment of an expandable conduit is illustrated in FIGS.2-6 and designated by reference number 20. The expandable conduit 20includes a proximal wall portion 22, which has a tubular configuration,and a distal wall portion, which is an expandable skirt portion 24. Theskirt portion 24 is enlargeable from a reduced profile configurationhaving an initial dimension 26 and corresponding cross-sectional area(illustrated in FIG. 2), to an enlarged configuration having a dimension28 and corresponding cross-sectional area (illustrated in FIG. 4). Inone embodiment, the skirt portion 24 is attached to the proximal wallportion 22 with a rivet 30, pin, or similar connecting device to permitmovement of the skirt portion 24 relative to the proximal wall portion22.

[0065] In the illustrated embodiment, the skirt portion 24 ismanufactured from a resilient material, such as stainless steel. Theskirt portion 24 is manufactured so that it normally assumes an expandedconfiguration illustrated in FIG. 4. As illustrated in FIG. 3, the skirtportion 24 may assume an intermediate dimension 34 and correspondingcross-sectional area, which is greater than the dimension 26 of thereduced profile configuration of FIG. 2, and smaller than the dimension28 of the enlarged configuration of FIG. 4. The skirt portion 24 mayassume the intermediate configuration of FIG. 3 when deployed in thepatient in response to the force of the tissue acting on the skirtportion 24. The intermediate dimension 34 will depend upon severalfactors, including the rigidity of the skirt portion 24, the surroundingtissue, and whether such surrounding tissue has relaxed or tightenedduring the course of the procedure. An outer plastic sleeve 32(illustrated in dashed line in FIG. 2) may be provided which surroundsthe expandable conduit 20 and maintains the skirt portion 24 in thereduced profile configuration. The outer sleeve 32 may have a braidedpolyester suture embedded within it (not shown), aligned substantiallyalong the longitudinal axis thereof; such that when the suture iswithdrawn, the outer sleeve 32 is torn, which allows the expandableconduit 20 to resiliently expand from the reduced profile configurationof FIG. 2 to the expanded configurations of FIGS. 3-4. While in thereduced profile configuration of FIG. 2, the skirt portion 24 defines afirst overlapping configuration 33, as illustrated by the dashed line.As the skirt portion 24 resiliently expands, the skirt portion 24assumes the expanded configuration, as illustrated in FIGS. 3-4.

[0066] The skirt portion 24 is sufficiently rigid that it is capable ofdisplacing the tissue surrounding the skirt portion 24 as it expands.Depending upon the resistance exerted by surrounding tissue, the skirtportion is sufficiently rigid to provide some resistance against thetissue to remain in the configurations of FIGS. 3-4. Moreover, theexpanded configuration of the skirt portion 24 is at least partiallysupported by the body tissue of the patient. The rigidity of the skirtportion 24 and the greater expansion at the distal portion creates astable configuration that is at least temporarily stationary in thepatient, which frees the physician from the need to actively support theconduit 20 until an endoscope mount platform 300 and a support arm 400are subsequently added in one embodiment (see FIGS. 21-22).

[0067] The skirt portion 24 of the expandable conduit 20 is illustratedin an initial flattened configuration in FIG. 5. The skirt portion 24may be manufactured from a sheet of stainless steel having a thicknessof about 0.007 inches. In various embodiments, the dimension 28 of theskirt portion 24 is about equal to or greater than 50 mm, is about equalto or greater than 60 mm, is about equal to or greater than 70 mm, isabout equal to or greater than 80 mm, or is any other suitable size,when the skirt portion 24 is in the enlarged configuration. In oneembodiment, the dimension 28 is about 63 mm, when the skirt portion 24is in the enlarged configuration. As discussed above, the unrestrictedshape of the skirt portion 24 preferably is a circular or an oblongshape. The skirt portion 24 may also take on an oval shape, wherein thedimension 28 would define a longer dimension the skirt portion 24 andwould be about 85 mm in one embodiment. In another embodiment, the skirtportion 24 has an oval shape and the dimension 28 defines a longerdimension of the skirt portion 24 and would be about 63 mm. An increasedthickness, e.g., about 0.010 inches, may be used in connection withskirt portions having a larger diameter, such as about 65 mm. Othermaterials, such as nitinol or plastics having similar properties, mayalso be useful.

[0068] As discussed above, the skirt portion 24 is attached to theproximal wall portion 22 with a pivotable connection, such as rivet 30.A pair of rivet holes 36 are provided in the skirt portion 24 to receivethe rivet 30. The skirt portion 24 also has two free ends 38 and 40 inone embodiment that are secured by a slidable connection, such as secondrivet 44 (not shown in FIG. 5, illustrated in FIGS. 2-4). A pair ofcomplementary slots 46 and 48 are defined in the skirt portion 24adjacent the free ends 38 and 40. The rivet 44 is permitted to movefreely within the slots 46 and 48. This slot and rivet configurationallows the skirt portion 24 to move between the reduced profileconfiguration of FIG. 2 and the enlarged or expanded configurations ofFIGS. 3-4. The use of a pair of slots 46 and 48 reduces the risk of the“button-holing” of the rivet 44, e.g., a situation in which the openingof the slot becomes distorted and enlarged such that the rivet may slideout of the slot, and cause failure of the device. However, thelikelihood of such occurrence is reduced in skirt portion 24 becauseeach of the slots 46 and 48 in the double slot configuration has arelatively shorter length than a single slot configuration. Beingshorter, the slots 46, 48 are less likely to be distorted to the extentthat a rivet may slide out of position. In addition, the configurationof rivet 44 and slots 46 and 48 permits a smoother operation ofenlarging and reducing the skirt portion 24, and allows the skirtportion 24 to expand to span as many as three vertebrae, e.g., L4, L5,and S1, to perform multi-level fixation alone or in combination with avariety of other procedures, as discussed below.

[0069] An additional feature of the skirt portion 24 is the provision ofa shallow concave profile 50 defined along the distal edge of the skirtportion 24, which allows for improved placement of the skirt portion 24with respect to the body structures and the surgical instruments definedherein. In one embodiment, a pair of small scalloped or notched portions56 and 58, are provided, as illustrated in FIG. 5. When the skirtportion 24 is assembled, the notched portions 56 and 58 are oriented inthe cephcaudal direction (indicated by an arrow 60 in FIG. 4) and permitinstrumentation, such as an elongated member 650 used in a fixationprocedure (described in detail below), to extend beyond the areaenclosed by the skirt portion 24 without moving or raising the skirtportion 24 from its location to allow the elongated member 650 to passunder the skirt portion 24. The notched portions 56, 58 are optional, asillustrated in connection with another embodiment of an expandableconduit 54, illustrated in FIG. 6, and may be eliminated where thephysician deems the notches to be unnecessary for the procedures to beperformed (e.g., where fixation does not require extended access, asdiscussed more fully below.)

[0070] As illustrated in FIG. 4, the skirt portion 24 may be expanded toa substantially conical configuration having a substantially circular orelliptical profile. In another embodiment, features may be provided onthe skirt portion which facilitate the bending of the skirt portion atseveral locations to provide a pre-formed enlarged configuration. Forexample, another embodiment of an expandable conduit 70, illustrated inFIGS. 7-9, provides a skirt portion 74 that has four sections 76 a, 76b, 76 c, 76 d having a reduced thickness. For a skirt portion 74 havinga thickness 78 of about 0.007 inches, reduced thickness sections 76 a,76 b, 76 c, 76 d may have a thickness 80 of about 0.002-0.004 inches(FIG. 8). The reduced thickness sections 76 a, 76 b, 76 c, 76 d may havea width 82 of about 1-5 mm. The thickness 78 of the skirt portion 74 maybe reduced by milling or grinding, as is known in the art. When theskirt portion 74 is opened, it moves toward a substantially rectangularconfiguration, as shown in FIG. 9, subject to the resisting forces ofthe body tissue. In another embodiment (not shown), a skirt portion maybe provided with two reduced thickness sections (rather than the fourreduced thickness sections of skirt 74) which would produce asubstantially “football”-shaped access area.

[0071] FIGS. 10-12 show another embodiment of an expandable conduit 80.The expandable conduit 80 has a skirt portion 84 with a plurality ofperforations 86. The perforations 86 advantageously increase theflexibility at selected locations. The size and number of perforations86 may vary depending upon the desired flexibility and durability. Inanother embodiment, the skirt portion 84 may be scored or otherwiseprovided with a groove or rib in order to facilitate the bending of theskirt portion at the desired location.

[0072]FIG. 13 illustrates another embodiment of an expandable conduitthat has a skirt portion 94 having one slot 96 and an aperture 98. Arivet (not shown) is stationary with respect to the aperture 98 andslides within the slot 96. FIG. 14 illustrates another embodiment of anexpandable conduit that has a skirt portion 104 that includes anaperture 108. The apertures 108 receives a rivet (not shown) that slideswithin elongated slot 106.

[0073] Further details of the expandable conduit are described in U.S.Pat. No. 6,187,00, and in U.S. patent application Ser. No. 09/772,605,filed Jan. 30, 2001, U.S. application Ser. No. 10/361,887 filed Feb. 10,2003, and application Ser. No. 10/280,489 filed Oct. 25, 2002, which areincorporated by reference in their entirety herein.

[0074] In one embodiment of a procedure, an early stage involvesdetermining a point in the skin of the patient at which to insert theexpandable conduit. The access point preferably corresponds to theposterior-lateral aspects of the spine. Manual palpation andAnterior-Posterior (AP) fluoroscopy may be used to determine preferredor optimal locations for forming an incision in the skin of the patient.In one embodiment, the expandable conduit 20 preferably is placed midway(in the cephcaudal direction) between the L4 through S1 vertebrae,centrally about 4-7 cm from the midline of the spine.

[0075] After the above-described location is determined, an incision ismade at the location. A guide wire (not shown) is introduced underfluoroscopic guidance through the skin, fascia, and muscle to theapproximate surgical site. A series of dilators is used to sequentiallyexpand the incision to the desired width, about 23 mm in one procedure,without damaging the structure of surrounding tissue and muscles. Afirst dilator is placed over the guide wire, which expands the opening.The guide wire is then subsequently removed. A second dilator that isslightly larger than the first dilator is placed over the first dilator,which expands the opening further. Once the second dilator is in place,the first dilator is subsequently removed. This process of (1)introducing a next-larger-sized dilator coaxially over the previousdilator and (2) subsequently removing the previous dilator when thenext-larger-sized dilator is in place continues until an opening of thedesired size is created in the skin, muscle, and subcutaneous tissue. Inone embodiment of the method, desired opening size is about 23 mm.(Other dimensions of the opening, e.g., about 20 mm, 27 mm, 30 mm, etc.,are also useful with this apparatus in connection with spinal surgery,and still other dimensions are contemplated.)

[0076]FIG. 15 shows that following placement of a dilator 120, which isthe largest dilator in the above-described dilation process, theexpandable conduit 20 is introduced in its reduced profile configurationand positioned in a surrounding relationship over the dilator 120. Thedilator 120 is subsequently removed from the patient, and the expandableconduit 20 is allowed to remain in position.

[0077] Once positioned in the patient, the expandable conduit 20 may beenlarged to provide a passage for the insertion of various surgicalinstruments and to provide an enlarged space for performing theprocedures described herein. As described above, the expandable conduitmay achieve the enlargement in several ways. In one embodiment, a distalportion of the conduit may be enlarged, and a proximal portion maymaintain a constant diameter. The relative lengths of the proximalportion 22 and the skirt portion 24 may be adjusted to vary the overallexpansion of the conduit 20. Alternatively, such expansion may extendalong the entire length of the expandable conduit 20. In one embodimentof a procedure, the expandable conduit 20 may be expanded by removing asuture 35 and tearing the outer sleeve 32 surrounding the expandableconduit 20, and subsequently allowing the skirt portion 24 toresiliently expand towards its fully expanded configuration as(illustrated in FIG. 4) to create an enlarged surgical space from the L4to the S1 vertebrae. The resisting force exerted on the skirt portion 24may result in the skirt portion 24 assuming the intermediateconfiguration illustrated in FIG. 3. Under many circumstances, the spacecreated by the skirt portion 24 in the intermediate configuration is asufficiently large working space to perform the procedure describedherein. Once the skirt portion 24 has expanded, the rigidity andresilient characteristics of the skirt portion 24 allow the expandableconduit 20 to resist closing to the reduced profile configuration ofFIG. 2 and to at least temporarily resist being expelled from theincision. These characteristics create a stable configuration for theconduit 20 to remain in position in the body, supported by thesurrounding tissue. It is understood that additional support may beneeded, especially if an endoscope is added.

[0078] According to one embodiment of a procedures, the expandableconduit 20 may be further enlarged at the skirt portion 24 using anexpander apparatus to create a surgical access space. An expanderapparatus useful for enlarging the expandable conduit has a reducedprofile configuration and an enlarged configuration. The expanderapparatus is inserted into the expandable conduit in the reduced profileconfiguration, and subsequently expanded to the enlarged configuration.The expansion of the expander apparatus also causes the expandableconduit to be expanded to the enlarged configuration. In someembodiments, the expander apparatus may increase the diameter of theexpandable conduit along substantially its entire length in a conicalconfiguration. In other embodiments, the expander apparatus expands onlya distal portion of the expandable conduit, allowing a proximal portionto maintain a constant diameter.

[0079] In addition to expanding the expandable conduit, the expanderapparatus may also be used to position the distal portion of theexpandable conduit at the desired location for the surgical procedure.The expander engages an interior wall of the expandable conduit, andmoves the conduit to the proper location. For the embodiments in whichthe distal portion of the expandable conduit is relatively movable withrespect to the proximal portion, the expander apparatus is useful toposition the distal portion without substantially disturbing theproximal portion.

[0080] In some procedures, an expander apparatus is used to furtherexpand the skirt portion 24 towards the enlarged configuration(illustrated in FIG. 4). The expander apparatus is inserted into theexpandable conduit, and typically has two or more members which aremovable to engage the interior wall of the skirt portion 24 and apply aforce sufficient to further expand the skirt portion 24. FIGS. 16 and 17show one embodiment of an expander apparatus 200 that has a firstcomponent 202 and a second component 204. a first component 202 and asecond component 204 of the expander apparatus 200 are arranged in atongs-like configuration and are pivotable about a pin 206. The firstand second components 202 and 204 are typically constructed of steelhaving a thickness of about 9.7 mm. Each of the first and secondcomponents 202 and 204 has a proximal handle portion 208 and a distalexpander portion 210. Each proximal handle portion 208 has a finger grip212 that may extend transversely from an axis, e.g., a longitudinal axis214, of the apparatus 200. The proximal handle portion 208 may furtherinclude a stop element, such as flange 216, that extends transverselyfrom the longitudinal axis 214. The flange 216 is dimensioned to engagethe proximal end 25 of the expandable conduit 20 when the apparatus 200is inserted a predetermined depth. This arrangement provides a visualand tactile indication of the proper depth for inserting the expanderapparatus 200. In one embodiment, a dimension 218 from the flange 216 tothe distal tip 220 is about 106 mm. The dimension 218 is determined bythe typical depth of the body structures beneath the skin surface atwhich the surgical procedure is being performed. The distal portions 210are each provided with an outer surface 222 for engaging the inside wallof the skirt portion 24. The outer surface 222 is a frusto-conicalsurface in one embodiment. The expander apparatus 200 has an unexpandeddistal width 224 at the distal tip 220 that is about 18.5 mm in oneembodiment.

[0081] In use, the finger grips 212 are approximated towards oneanother, as indicated by an arrow A in FIG. 17, which causes the distalportions 210 to move to the enlarged configuration, as indicated byarrows B. The components 202 and 204 are also provided with acooperating tab 226 and shoulder portion 228 which are configured formutual engagement when the distal portions 210 are in the expandedconfiguration. In the illustrated embodiment, the expander apparatus 200has an expanded distal width 230 that extends between the distalportions 210. The expanded distal width 230 can be about 65 mm or less,about as large as 83 mm or less, or any other suitable width. The tab226 and shoulder portion 228 together limit the expansion of theexpander apparatus 200 to prevent expansion of the skirt portion 24 ofthe expandable conduit 20 beyond its designed dimension, and to minimizetrauma to the underlying tissue. Further details of the expanderapparatus are described in U.S. patent application Ser. No. 09/906,463filed Jul. 16, 2001, which is incorporated by reference in theirentirety herein.

[0082] When the expandable conduit 20 is inserted into the patient andthe outer sleeve 32 is removed, the skirt portion 24 expands to a pointwhere the outward resilient expansion of the skirt portion 24 isbalanced by the force of the surrounding tissue. The surgical spacedefined by the conduit may be sufficient to perform any of a number ofsurgical procedures or combination of surgical procedures describedherein. However, if it is desired to expand the expandable conduit 20further, the expander apparatus 200 may be inserted into the expandableconduit 20 in the reduced profile configuration until the shoulderportions 216 are in approximation with the proximal end 25 of the skirtportion 24 of the expandable conduit 20, as shown in FIG. 18.

[0083]FIG. 18 shows the expander apparatus 200 is inserted in theexpandable conduit 20 in the reduced profiled configuration. Expansionof the expander apparatus 200 is achieved by approximating the handleportions 212 (not shown in FIG. 18), which causes the distal portions210 of the expander apparatus 200 to move to a spaced apartconfiguration. As the distal portions 210 move apart and contact theinner wall of the skirt portion 24, the skirt portion 24 is expanded byallowing the rivet 44 to slide within the slots 46 and 48 of the skirtportion 24. When the distal portions 210 reach the maximum expansion ofthe skirt portion 24 (illustrated by a dashed line in FIG. 19), the tab226 and shoulder portion 228 of the expander apparatus 200 come intoengagement to prevent further expansion of the tong portions (asillustrated in FIG. 17). The conduit 20 may be alternatively furtherexpanded with a balloon or similar device.

[0084] A subsequent, optional step in the procedure is to adjust thelocation of the distal portion of the expandable conduit 20 relative tothe body structures to be operated on. For example, the expanderapparatus 200 may also be used to engage the inner wall of the skirtportion 24 of the expandable conduit 20 in order to move the skirtportion 24 of the expandable conduit 20 to the desired location. For anembodiment in which the skirt portion 24 of the expandable conduit 20 isrelatively movable relative to the proximal portion, e.g. by use of therivet 30, the expander apparatus 200 is useful to position the skirtportion 24 without substantially disturbing the proximal portion 22 orthe tissues closer to the skin surface of the patient. As will bedescribed below, the ability to move the distal end portion, e.g., theskirt portion 24, without disturbing the proximal portion is especiallybeneficial when an additional apparatus is mounted relative to theproximal portion of the expandable conduit, as described below.

[0085] An endoscope mount platform 300 and indexing arm 400 providesecurement of an endoscope 500 on the proximal end 25 of the expandableconduit 20 for remotely viewing the surgical procedure, as illustratedin FIGS. 20-23. The endoscope mount platform 300 may also provideseveral other functions during the surgical procedure. The endoscopemount platform 300 includes a base 302 that extends laterally from acentral opening 304 in a general ring-shaped configuration. The base 302provides an aid for the physician, who is primarily viewing theprocedure by observing a monitor, when inserting surgical instrumentsinto the central opening 304. For example, the size of the base 302provides visual assistance (as it may be observable in the physician'speripheral vision) as well as provides tactile feedback as theinstruments are lowered towards the central opening 304 and into theexpandable conduit 20.

[0086] The endoscope mount platform 300 further provides a guide portion306 that extends substantially parallel to a longitudinal axis 308 awayfrom the central opening 304. The base 302 is typically molded as onepiece with the guide portion 306. The base 302 and guide portion 306 maybe constructed as a suitable polymer such as polyetheretherketone(PEEK).

[0087] The guide portion 306 includes a first upright member 310 thatextends upward from the base 302 and a second upright member 312 thatextends upward from the base 302. The upright members 310, 312 each havea respective vertical grooves 314 and 315 that can slidably receive anendoscopic mount assembly 318.

[0088] The endoscope 500 (not shown in FIG. 20) is movably mounted tothe endoscope mount platform 300 by the endoscope mount assembly 318.The endoscope mount assembly 318 includes an endoscope mount 320 and asaddle unit 322. The saddle unit 322 is slidably mounted is within thegrooves 314 and 315 in the upright members 310 and 312. The endoscopemount 320 receives the endoscope 500 through a bore 326 which passesthrough the endoscope mount 320. Part of the endoscope 500 may extendthrough the expandable conduit 20 substantially parallel to longitudinalaxis 308 into the patient's body 130.

[0089] The endoscope mount 320 is removably positioned in a recess 328defined in the substantially “U”-shaped saddle unit 322, which isselectively movable in a direction parallel to the longitudinal axis 308in order to position the endoscope 500 at the desired height within theexpandable conduit 20 to provide a zoom feature to physician's view ofthe surgical procedure.

[0090] A screw mechanism 340 is positioned on the base 302 between theupright members 310 and 312, and is used to selectively move the saddleunit 322, and the endoscope mount 320 and the endoscope 500 which aresupported by the saddle unit 322. The screw mechanism 340 comprises athumb wheel 342 and a spindle 344. The thumb wheel 343 is rotatablymounted in a bore in the base 302. The thumb wheel 342 has an externalthread 346 received in a cooperating thread in the base 302. The spindle344 is mounted for movement substantially parallel to the central axis308. The spindle 344 has a first end received in a rectangular openingin the saddle unit 322, which inhibits rotational movement of thespindle 344. The second end of the spindle 344 has an external threadwhich cooperates with an internal thread formed in a bore within thethumb wheel 342. Rotation of the thumb wheel 342 relative to the spindle344, causes relative axial movement of the spindle unit 344 along withthe saddle unit 322. Further details of the endoscope mount platform aredescribed in U.S. patent application Ser. No. 09/491,808 filed Jan. 28,2000, application Ser. No. 09/821,297 filed Mar. 29, 2001, andapplication Ser. No. 09/940,402 filed Aug. 27, 2001.

[0091] FIGS. 21-23 show that the endoscope mount platform 300 ismountable to the support arm 400 in one embodiment. The support arm 400,in turn, preferably is mountable to mechanical support, such asmechanical support arm A, discussed above in connection with FIG. 1. Thesupport arm 400 rests on the proximal end 25 of the expandable conduit20. The support arm 400 includes an indexing collar 420, which isreceived in the central opening 304 of the base 302 of endoscope mountplatform 300. The indexing collar 420 is substantially toroidal insection and has an outer peripheral wall surface 422, an inner wallsurface 424, and a wall thickness 426 that is the distance between thewall surfaces 422, 424. The indexing collar 420 further includes aflange 428, which supports the indexing collar 420 on the support arm400.

[0092] The collars 420 advantageously make the surgical system 10 amodular in that different expandable conduits 20 may be used with asingle endoscope mount platform 300. For example, expandable conduits 20of different dimensions may be supported by providing of indexingcollars 420 to accommodate each conduit size while using a singleendoscope mount platform 300. The central opening 304 of the endoscopemount platform 300 has constant dimension, e.g., a diameter of about32.6 mm. An appropriate indexing collar 420 is selected, e.g., one thatis appropriately sized to support a selected expandable conduit 20. Thusthe outer wall 422 and the outer diameter 430 are unchanged betweendifferent indexing collars 420, although the inner wall 424 and theinner diameter 432 vary to accommodate differently sized conduits 20.

[0093] The indexing collar 420 is mounted to the proximal portion of theexpandable conduit 20 and allows angular movement of the endoscope mountplatform 300 with respect thereto about the longitudinal axis 308 (asindicated by an arrow C in FIG. 21). The outer wall 422 of the indexcollar 420 includes a plurality of hemispherical recesses 450 that canreceive one or more ball plungers 350 on the endoscope mount platform300 (indicated in dashed line.) This arrangement permits the endoscopemount platform 300, along with the endoscope 500, to be fixed in aplurality of discrete angular positions. Further details of the supportarm and indexing collar are described in U.S. Pat. No. 6,361,488, issuedMar. 26, 2002, U.S. Pat. No. 6,530,880 issued Mar. 11, 2003, andapplication Ser. No. 09/940,402 filed Aug. 27, 2001.

[0094]FIG. 24 shows one embodiment of the endoscope 500, which has anelongated configuration that extends into the expandable conduit 20 inorder to view the surgical site. In particular, the endoscope 500 has anelongated rod portion 502 and a body portion 504 which is substantiallyperpendicular thereto. In the illustrated embodiment, the rod portion502 of endoscope 500 has a diameter of about 4 mm and a length of about106 mm. Body portion 504 may define a tubular portion 506 which isconfigured to be slidably received in the bore 326 of endoscope mount320 as indicated by an arrow D. The slidable mounting of the endoscope500 on the endoscope mount platform 300 permits the endoscope 500 toadjust to configurations that incorporate different conduit diameters.Additional mobility of the endoscope 500 in viewing the surgical sitemay be provided by rotating the endoscope mount platform 300 about thecentral axis 308 (as indicated by arrow C in FIG. 21).

[0095] The rod portion 502 supports an optical portion (not shown) at adistal end 508 thereof, which may define a field of view of about 105degrees and a direction of view 511 of about 25-30 degrees. An eyepiece512 is positioned at an end portion of the body portion 504. A camera(not shown) preferably is attached to the endoscope 500 adjacent theeyepiece 512 with a standard coupler unit. A light post 510 suppliesillumination to the surgical site at the distal end portion 508. Apreferred camera for use in the system and procedures described hereinis a three chip unit that provides greater resolution to the viewedimage than a single chip device.

[0096] A subsequent stage in the procedure involves placing the supportarm 400 and the endoscope mount platform 300 on the proximal portion,e.g., the proximal end 25, of the expandable conduit 20 (FIGS. 1 and22), and mounting of the endoscope 500 on the endoscope mount platform300. A next step is insertion of one or more surgical instruments intothe expandable conduit 20 to perform the surgical procedure on the bodystructures at least partially within the operative space defined by theexpanded portion of the expandable conduit. FIG. 25 shows that in onemethod, the skirt portion 24 of expandable conduit 20 at least partiallydefines a surgical site or operative space 90 in which the surgicalprocedures described herein may be performed. Depending upon the overlapof the skirt portion, the skirt portion may define a surface which iscontinuous about the circumference or which is discontinuous having oneor more gaps where the material of the skirt portion does not overlap.

[0097] One procedure performable through the expandable conduit 20,described in greater detail below, is a two-level spinal fixation.Surgical instruments inserted into the expandable conduit may be usedfor debridement and decortication. In particular, the soft tissue, suchas fat and muscle, covering the vertebrae may be removed in order toallow the physician to visually identify the various “landmarks,” orvertebral structures, which enable the physician to locate the locationfor attaching a fastener, such a fastener 600, discussed below, or otherprocedures, as will be described herein. Allowing visual identificationof the vertebral structures enables the physician to perform theprocedure while viewing the surgical area through the endoscope,microscope, loupes, etc., or in a conventional, open manner.

[0098] Tissue debridement and decortication of bone are completed usingone or more debrider blades, bipolar sheath, high speed burr, andadditional conventional manual instruments. The debrider blades are usedto excise, remove and aspirate the soft tissue. The bipolar sheath isused to achieve hemostasis through spot and bulk tissue coagulation. Thedebrider blades and bipolar sheath are described in greater detail inU.S. Pat. No. 6,193,715, assigned to Medical Scientific, Inc., which isincorporated by reference in its entirety herein. The high speed burrand conventional manual instruments are also used to continue to exposethe structure of the vertebrae.

[0099] A subsequent stage is the attachment of fasteners to thevertebrae V. Prior to attachment of the fasteners, the location of thefastener attachment is confirmed. In the exemplary embodiment, thepedicle entry point of the L5 vertebrae is located using visuallandmarks as well as lateral and A/P fluoroscopy, as is known in theart. With continued reference to FIG. 25, the entry point 92 is preparedwith an awl 550. The pedicle hole 92 is completed using instrumentsknown in the art such as a straight bone probe, a tap, and a sounder.The sounder, as is known in the art, determines whether the hole that ismade is surrounded by bone on all sides, and that there has been noperforation of the pedicle wall.

[0100] After hole in the pedicle is provided at the entry point 92 (orat any point during the procedure), an optional step is to adjust thelocation of the distal portion of the expandable conduit 20. This may beperformed by inserting the expander apparatus 200 into the expandableconduit 20, expanding the distal portions 210, and contacting the innerwall of the skirt portion 24 to move the skirt portion 24 to the desiredlocation. This step may be performed while the endoscope 500 ispositioned within the expandable conduit 20, and without substantiallydisturbing the location of the proximal portion of the expandableconduit 20 to which the endoscope mount platform 300 may be attached.

[0101] FIGS. 26-27 illustrate a fastener 600 that is particularlyapplicable in a procedures involving fixation. The fastener 600 isdescribed in greater detail in U.S. patent application Ser. No.10/075,668, filed Feb. 13, 2002 and application Ser. No. 10/087,489,filed Mar. 1, 2002, which are incorporated by reference in theirentirety herein. Fastener 600 includes a screw portion 602, a housing604, a spacer member 606, a biasing member 608, and a clamping member,such as a cap screw 610. The screw portion 602 has a distal threadedportion 612 and a proximal, substantially spherical joint portion 614.The threaded portion 612 is inserted into the hole 92 in the vertebrae,as will be described below. The substantially spherical joint portion614 is received in a substantially annular, part spherical recess 616 inthe housing 604 in a ball and socket joint relationship (see also FIG.29).

[0102] As illustrated in FIG. 27, the fastener 600 is assembled byinserting the screw portion 602 into a bore in a passage 618 in thehousing 604, until the joint portion 614 engages the annular recess 616.The screw portion 602 is retained in the housing 604 by the spacermember 606 and biasing member 608. The biasing member 608 provides abiasing force to drive the spacer member 606 in frictional engagementwith the joint portion 614 of the screw member 602 and the annularrecess 616 of the housing 604. The biasing provided by the biasingmember 602 frictionally maintains the relative positions of the housing604 with respect to the screw portion 602. The biasing member 608 isselected such that biasing force prevents unrestricted movement of thehousing 604 relative to the screw portion 602. However, the biasingforce is insufficient to resist the application of force by a physicianto move the housing 604 relative to the screw portion 602. In otherwords, this biasing force is strong enough maintain the housing 604stationary relative to the screw portion 602, but this force may beovercome by the physician to reorient the housing 604 with respect tothe screw member 602, as will be described below.

[0103] In the illustrated embodiment, the biasing member 608 is aresilient ring having a gap 620, which permits the biasing member 608 toradially contract and expand. FIG. 27(a) illustrates that the biasingmember 608 may have an arched shape, when viewed end-on. The archedshape of the spring member 608 provides the biasing force, as will bedescribed below. The spacer member 606 and the biasing member 608 areinserted into the housing 604 by radially compressing the biasing memberinto an annular groove 622 in the spacer member 606. The spacer member606 and the biasing member 608 are slid into the passage 618 until thedistal surface of the spacer member 606 engages the joint portion 614 ofthe screw portion 602, and the biasing member 608 expands radially intothe annular groove 622 in the housing 604. The annular groove 622 in thehousing 604 has a dimension 623 which is smaller than the uncompressedheight of the arched shape of the biasing member 608. When the biasingmember 608 is inserted in the annular groove 620, the biasing member 608is flattened against its normal bias, thereby exerting the biasing forceto the spacer member 606. It is understood that similar biasing members,such as coiled springs, belleville washers, or the like may be used tosupply the biasing force described herein.

[0104] The spacer member 606 is provided with a longitudinal bore 626,which provides access to a hexagonal recess 628 in the proximal end ofthe joint portion 614 of the screw member 602. The proximal portion ofthe housing 604 includes a pair of upright members 630 and 631 that areseparated by substantially “U”-shaped grooves 632. A recess forreceiving elongated member 650 is defined by the pair of grooves 632between upright member 630 and 631. Elongated member 650 to be placeddistally into the housing 604 in an orientation substantially transverseto the longitudinal axis of the housing 604, as will be described below.The inner walls of he upright members 630 and 631 are provided withthreads 634 for attachment of the cap screw 610 by threads 613 therein.

[0105] The fastener 600 is inserted into the expandable conduit 20 andguided to the prepared hole 92 in the vertebrae as a further stage ofthe procedure. The fastener 600 must be simultaneously supported androtated in order to be secured in hole 92. In the illustrated embodimentthe fastener 600 is supported and attached to the bone by an endoscopicscrewdriver apparatus 660, illustrated in FIGS. 28-29. The screwdriver660 includes a proximal handle portion 662 (illustrated in dashed line),an elongated body portion 664, and a distal tool portion 666.

[0106] The distal tool portion 666, as illustrated in greater detail inFIG. 29 includes a substantially hexagonal outer periphery which isreceived in the substantially hexagonal recess 628 in the joint portion614 of the screw member 602. A spring member at the distal tool portion666 releasably engages the hexagonal recess 628 of the screw member 602to support the fastener 600 during insertion and tightening. In theillustrated embodiment, a spring member 672 is configured to engage theside wall of the recess 628. More particularly, a channel/groove isprovided in the tip portion 666 for receiving the spring member 672. Thechannel/groove includes a medial longitudinal notch portion 676, aproximal, angled channel portion 678, and a distal substantiallytransverse channel portion 680. The spring member 672 is preferablymanufactured from stainless steel and has a medial portion 682 that ispartially received in the longitudinal notch portion 676, an angledproximal portion 684 which is fixedly received in the angled charnelportion 678, and a transverse distal portion 686 which is slidablyreceived in the transverse channel 680. The medial portion 682 of thespring member 672 is partially exposed from the distal tip portion 666and normally biased in a transverse outward direction with respect tothe longitudinal axis (indicated by arrow E), in order to supply bearingforce against the wall of the recess 628. Alternatively the distal tipportion of the screw driver may be magnetized in order to hold the screwportion 602. Similarly, the distal tip portion may include a ballbearing or similar member which is normally biased in a radially outwarddirection to engage the interior wall of the recess 628 to secure thefastener 600 to the screwdriver distal tip 666.

[0107] The insertion of the fastener 600 into the prepared hole 92 maybe achieved by insertion of screwdriver 660 into conduit 20 (indicatedby arrow G). This procedure may be visualized by the use of theendoscope 500 in conjunction with fluoroscopy. The screw portion 602 isthreaded into the prepared hole 92 by the endoscopic screwdriver 660(indicated by arrow H). The endoscopic screwdriver 660 is subsequentlyseparated from the fastener 600, by applying a force in the proximaldirection, and thereby releasing the distal tip portion 666 from thehexagonal recess 628 (e.g., causing the transverse distal portion 686 ofthe spring member 672 to slide within the transverse recess 680 againstthe bias, indicated by arrow F), and removing the screwdriver 660 fromthe expandable conduit 20. An alternative method may use a guidewire,which is fixed in the hole 92, and a cannulated screw which has aninternal lumen (as is known in the art) and is guided over the guidewireinto the hole 92. The screwdriver would be cannulated as well to fitover the guidewire.

[0108] For a two-level fixation, it may be necessary to prepare severalholes and attach several fasteners 600. Typically, the expandableconduit 20 will be sized in order to provide simultaneous access to allvertebrae in which the surgical procedure is being performed. In somecases, however, additional enlargement or repositioning of the distalportion of the expandable conduit may be required in order to havesufficient access to the outer vertebrae, e.g., the L4 and S1 vertebrae.In the illustrated embodiment, the expander apparatus 200 may berepeatedly inserted into the expandable conduit 20 and expanded in orderto further open or position the skirt portion 24. In one procedure,additional fasteners are inserted in the L4 and S1 vertebrae in asimilar fashion as the fastener 600 inserted in to the L5 vertebra asdescribed above. (When discussed individually or collectively, afastener and/or its individual components will be referred to by thereference number, e.g., fastener 600, housing 604, and all fasteners600. However, when several fasteners and/or their components arediscussed in relation to one another, an alphabetic subscript will beused, e.g., fastener 600 a is moved towards fastener 600 b.)

[0109] In a further stage of the procedure, the housing portions 604 ofthe fasteners 600 are substantially aligned such that their uprightportions 630 and 631 face upward, and the notches 632 are substantiallyaligned to receive the elongated member 650 therein. The frictionalmounting of the housing 604 to the screw member 602, described above,allows the housing 604 to be temporarily positioned until a subsequenttightening step, described below. Positioning of the housing portions604 may be performed by the use of an elongated surgical instrumentcapable of contacting and moving the housing portion to the desiredorientation. One such instrument for positioning the housings 604 is agrasper apparatus 700, illustrated in FIG. 30. The grasper apparatus 700includes a proximal handle portion 702, an elongated body portion 704,and distal nose portion 706. The distal nose portion 706 includes a pairof grasping jaws 708 a and 708 b, which are pivotable about pin 710 byactuation of the proximal handle portion 702. The grasping jaws 708 aand 708 b are illustrated in the closed position in FIG. 30. As is knownin the art, pivoting the movable handle 714 towards stationary handle714 causes longitudinal movement of actuator 716, which in turn pivotsthe jaw 708 b towards an open position (illustrated in dashed line). Thebiasing members 718 and 720 are provided to return the handles 712 and714 to the open position and bias the jaws 708 a and 708 b to the closedposition.

[0110] A subsequent stage in the process is the insertion of theelongated member 650 into the expandable conduit. The elongated member650 is manufactured from a biocompatible material and must besufficiently strong to maintain the positioning of the vertebrae, orother body structures. In the exemplary embodiment, the elongatedmembers 650 are manufactured from Titanium 6/4 or titanium alloy.Alternatively, the elongated member 650 may be manufactured fromstainless steel or other suitable material. The radii and length of theelongated members 650 are selected by the physician to provide the bestfit for the positioning of the screw heads. Such selection may beperformed by placing the elongated member 650 on the skin of the patientoverlying the location of the fasteners and viewed fluoroscopically. Forexample, a 70 mm preformed rod having a 3.5″ bend radius may be selectedfor the spinal fixation.

[0111] The elongated member 650 is subsequently fixed to each of thefasteners 600, and more particularly, to the housings 604 of eachfastener 600. The grasper apparatus 700, described above, is alsoparticularly useful for inserting the elongated member 650 into theexpandable conduit 20 and positioning it with respect to each housing604. As illustrated in FIG. 30, the jaws 708 a and 708 b of the grasperapparatus 700 each has a curved contact portion 722 a and 722 b forcontacting and holding the outer surface of the elongated member 650.

[0112] As illustrated in FIG. 31, the grasper apparatus 700 may be usedto insert the elongated member 650 into the operative space 90 definedat least partially by the skirt portion 24 of the expandable conduit 20.The cut-out portions 56 and 58 provided in the skirt portion 24 assistin the process of installing the elongated member 650 with respect tothe housings 604. The cut-out portions 56 and 58 allow an end portion652 of the elongated member 650 to extend beyond the operative spacewithout raising or repositioning the skirt portion 24. The elongatedmember 650 is positioned within the recesses in each housing 604 definedby grooves 632 disposed between upright members 630 and 631. Theelongated member 650 is positioned in an orientation substantiallytransverse to the longitudinal axis of each housing 604.

[0113] Further positioning of the elongated member 650 may be performedby guide apparatus 800, illustrated in FIG. 32. Guide apparatus 800 isuseful in cooperation with an endoscopic screwdriver, such as endoscopicscrewdriver 660 (illustrated in FIG. 28), in order to position theelongated member 650, and to introduce and tighten the cap screw 610,described above and illustrated in FIG. 27. Tightening of the cap screw610 with respect to the housing 604 fixes the orientation of the housing604 with respect to the screw portion 602 and fixes the position of theelongated member 650 with respect to the housing 604.

[0114] In the illustrated embodiment, the guide apparatus 800 has aproximal handle portion 802, an elongated body portion 804, and a distaltool portion 806. The elongated body portion 804 defines a central bore808 (illustrated in dashed line) along its longitudinal axis 810. Thecentral bore 808 is sized and configured to receive the endoscopicscrewdriver 660 and cap screw 610 therethrough. In the exemplaryembodiment, the diameter of the central bore 808 of the elongated bodyportion 804 is about 0.384-0.388 inches in diameter, and the externaldiameter of the endoscopic screwdriver 660 (FIG. 28) is about 0.25inches. The proximal handle portion 802 extends transverse to thelongitudinal axis 810, which allows the physician to adjust the guideapparatus 800 without interfering with the operation of the screwdriver660.

[0115] The distal portion 806 of the apparatus includes severalsemicircular cut out portions 814 which assist in positioning theelongated member 650. As illustrated in FIG. 33, the cut out portions814 are sized and configured to engage the surface of elongated member650 and move the elongated member 650 from an initial location(illustrated in dashed line) to a desired location.

[0116] As illustrated in FIG. 34, the guide apparatus 800 is used incooperation with the endoscopic screwdriver 660 to attach the cap screw610. The distal end of the body portion 804 includes a pair of elongatedopenings 816, which permit the physician to endoscopically view the capscrew 610 retained at the distal tip 666 of the endoscopic screw driver660.

[0117] The guide apparatus 800 and the endoscopic screwdriver 660 maycooperate as follows. The guide apparatus 800 is configured to bepositioned in a surrounding configuration with the screwdriver 600. Inthe illustrated embodiment, the body portion 804 is configured forcoaxial placement about the screwdriver 660 in order to distribute thecontact force of the guide apparatus 800 on the elongated member 650.The distal portion 806 of the guide apparatus 800 may bear down on theelongated member 650 to seat the elongated member 650 in the notches 632in the housing 604. The “distributed” force of the guide apparatus 800may contact the elongated member 650 on at least one or more locations.In addition, the diameter of central bore 808 is selected to bemarginally larger than the exterior diameter of cap screw 610, such thatthe cap screw 610 may freely slide down the central bore 808, whilemaintaining the orientation shown in FIG. 34. This configuration allowsthe physician to have effective control of the placement of the capscrew 610 into the housing 604. The cap screw 610 is releasably attachedto the endoscopic screwdriver 660 by means of spring member 672 engagedto the interior wall of hexagonal recess 611 as it is inserted withinthe bore 808 of the body portion 804 of guide apparatus 800. The capscrew 610 is attached to the housing 604 by engaging the threads 615 ofthe cap screw 610 with the threads 634 of the housing.

[0118] As illustrated in FIG. 35, tightening of the cap screw 610 fixesthe assembly of the housing 604 with respect to the elongated member650. In particular, the distal surface of the cap screw 610 provides adistal force against the elongated member 650, which in turn drives thespacer member 606 against the joint portion 614 of the screw portion602, which is consequently fixed with respect to the housing 604.

[0119] If locations of the vertebrae are considered acceptable by thephysician, then the fixation procedure is substantially complete oncethe cap screws 610 have been attached to the respective housings 604,and tightened to provide a fixed structure as between the elongatedmember 650 and the various fasteners 600. However, if compression ordistraction of the vertebrae with respect to one another is requiredadditional apparatus would be used to shift the vertebrae prior to finaltightening all of the cap screws 610.

[0120] In the illustrated embodiment, this step is performed with asurgical instrument, such as compressor-distractor instrument 900,illustrated in FIG. 36, which is useful to relatively position bonestructures in the cephcaudal direction and to fix their position withrespect to one another. Thus, the compressor-distractor instrument 900has the capability to engage two fasteners 600 and to space them apartwhile simultaneously tightening one of the fasteners to fix the spacingbetween the two vertebrae, or other bone structures. Moreover, thecompressor-distractor instrument 900 may also be used to move twofasteners 600, and the vertebrae attached thereto into closerapproximation and fix the spacing therebetween.

[0121] The distal tool portion 902 of the compressor-distractorinstrument 900 is illustrated in FIG. 36. (Further details of thecompressor-distractor apparatus is described in co-pending U.S.application Ser. No. 10/178,875, filed Jun. 24, 2002, entitled “SurgicalInstrument for Moving Vertebrae,” which is incorporatcd by refcrcncc inits cntircty herein.) The distal tool portion 902 includes a driverportion 904 and a spacing member 906. The driver portion 904 has adistal end portion 908 with a plurality of wrenching flats configured toengage the recess 611 in the proximal face of the cap screw 610, and toapply torque to the cap screw. The driver portion 904 is rotatable aboutthe longitudinal axis (indicated by arrow M) to rotate the cap screw 610relative to the fastener 600. Accordingly, the driver portion 904 can berotated to loosen the cap screw 610 on the fastener 600 and permitmovement of the elongated member 650 connected with the vertebrarelative to the fastener 600 connected with the vertebra. The cap screw610 can also be rotated in order to tighten the cap screw 610 and clampthe elongated member 650 to the fastener 600.

[0122] The distal tool portion 902 may also include a spacing member,such as spacing member 906, which engages an adjacent fastener 600 bwhile driver member 904 is engaged with the housing 604 a to move thefastener 600 b with respect to the fastener 600 a. In the exemplaryembodiment, spacing member 906 is a jaw portion which is pivotablymounted to move between a first position adjacent the driver portion anda second position spaced from the driver portion, as shown in FIG. 36.The distal tip 910 of the spacing member 906 is movable relative to thedriver portion 904 in a direction extending transverse to thelongitudinal axis.

[0123] As illustrated in FIG. 36, the spacer member 906 can be openedwith respect to the driver portion 904 to space the vertebrae furtherapart (as indicated by arrow N). The distal portion 910 of the spacermember 906 engages the housing 604 b of fastener 600 b and movesfastener 600 b further apart from fastener 600 a to distract thevertebrae. Where the vertebrae are to be moved closer together, e.g.compressed, the spacer member 906 is closed with respect to the driverportion 904 (arrow P), as illustrated in FIG. 37. The distal portion 610of spacer member 606 engages housing 604 b of fastener 600 b and movesfastener 600 b towards fastener 600 a. When the spacing of the vertebraeis acceptable to the physician, the cap screw 610 a is tightened by thedriver member 904, thereby fixing the relationship of the housing 604 awith respect to elongated member 650, and thereby fixing the position ofthe vertebrae, or other bone structures, with respect to one another.

[0124] Once the elongated member 650 is fixed with respect to thefasteners 600, the procedure is substantially complete. The surgicalinstrumentation, such as the endoscope 500 is withdrawn from thesurgical site. The expandable conduit 20 is also withdrawn from thesite. The muscle and fascia typically close as the expandable conduit 20is withdrawn through the dilated tissues in the reduced profileconfiguration. The fascia and skin incisions are closed in the typicalmanner, with sutures, etc. The procedure described above may be repeatedfor the other lateral side of the same vertebrae, if indicated.

II. Surgical Procedures that may be Performed with the Systems DescribedHerein

[0125] As discussed above, the systems disclosed herein provide accessto a surgical location at or near the spine of a patient to enableprocedures to be performed on the spine. These procedures can be appliedto one or more vertebral levels. Additional procedures and combinationsof procedures that may be performed using the systems described hereinare discussed below. In various forms, these procedures involve ananterior lumbar interbody fusion, a minimally invasive lumbar interbodyfusion, and other procedures particularly enabled by the access devicesand systems described above.

[0126] A. Procedures Involving Anterior Lumbar Interbody Fusion

[0127] The access devices and systems described herein are amenable to avariety of procedures that may be combined with an anterior lumbarinterbody fusion (referred to herein as an “ALIF”).

[0128] In one embodiment of a first method, three adjacent vertebrae,such as the L4, the L5, and the S1 vertebrae of the spine, are treatedby first performing an ALIF procedure. Such a procedure may be performedin a convention manner. The ALIF involves exposing a portion of thespine, in particular the vertebrae and discs located in the interbodyspaces, i.e., the spaces between adjacent vertebrae. Any suitabletechnique for exposing the interbody spaces may be employed, e.g., anopen, mini-open, or minimally invasive procedure. In one embodiment, theinterbody spaces between the L4, L5, and S1 vertebrae are exposed to thesurgeon. Once exposed, the surgeon may prepare the interbody space, ifneeded, in any suitable manner. For example, some or all of the disc maybe removed from the interbody space and the height of the interbodyspace may be increased or decreased. The interbody space between the L4and the L5 vertebrae may be exposed separately from the interbody spacebetween the L5 and S1 vertebrae or they may be generally simultaneouslyexposed and prepared.

[0129] After the interbody space has been exposed and prepared, asuitable fusion procedure may be performed. For example, in one examplefusion procedure, one or more fusion devices may be placed in theinterbody space. Any suitable fusion device may be used, e.g., a fusioncage, a femoral ring, or another suitable implant. Various embodimentsof implants and techniques and tools for the insertion of implants aredescribed in U.S. application Ser. No. 10/280,489, filed Oct. 25, 2002,which has been published as Publication No. 2003/0073998 on Apr. 17,2003, which is hereby incorporated by reference herein in its entirety.In one variation, one or more fusion cages may be placed in an interbodyspace, e.g., between the L4 and L5 vertebrae, between the L5 and S1vertebrae, or between the L4 and L5 vertebrae and between the L5 and S1vertebrae. In another variation, one or more femoral rings may besubstituted for one or more of the fusion cages and placed between theL4 and L5 vertebrae and/or between the L5 and S1 vertebrae. In anothervariation, one or more fusion devices are combined with a bone growthsubstance, e.g., bone chips, to enhance bone growth in the interbodyspace(s).

[0130] After anterior placement of the fusion device, an access deviceis inserted into the patient to provide access to a spinal location, asdescribed above. A variety of anatomical approaches may be used toprovide access to a spinal location using the expandable conduit 20. Theaccess device preferably is inserted generally posteriorly. As usedherein the phrase “generally posteriorly” used in its ordinary sense andis a broad term that refers to a variety of surgical approaches to thespine that may be provided from the posterior side, i.e., the back, ofthe patient, and includes, but is not limited to, posterior,postero-lateral, and transforaminal approaches. Any of the accessdevices described or incorporated herein, such as the expandable conduit20, could be used.

[0131] The distal end of the access device may be placed at the desiredsurgical location, e.g., adjacent the spine of the patient with acentral region of the access device over a first vertebrae. In oneprocedure, the distal end of the access device is inserted until itcontacts at least a portion of at least one of the vertebrae beingtreated or at least a portion of the spine. In another procedure, thedistal end of the access device is inserted until it contacts a portionof the spine and then is withdrawn a small amount to provide a selectedgap between the spine and the access device in other procedures, theaccess device may be inserted a selected amount, but not far enough tocontact the vertebrae being treated, the portion of the vertebrae beingtreated, or the spine.

[0132] The access device may be configured, as described above, toprovide increased access to the surgical location. The access device canhave a first configuration for insertion to the surgical location overthe first vertebra and a second configuration wherein increased accessis provided to the adjacent vertebrae. The first configuration mayprovide a first cross-sectional area at a distal portion thereof. Thesecond configuration may provide a second cross-sectional area at thedistal portion thereof. The second cross-sectional area preferably isenlarged compared to the first cross-sectional area. In someembodiments, the access device may be expanded from the firstconfiguration to the second configuration to provide access to theadjacent vertebrae above and below the first vertebra.

[0133] When it is desired to treat the L4, L5, and S1 vertebrae, theaccess device may be inserted over the L5 vertebrae and then expanded toprovide increased access to the L4 and S1 vertebrae. In one embodiment,the access device can be expanded to an oblong shaped configurationwherein the access device provides a first dimension of about 63 mm, anda second dimension perpendicular to the first dimension of about 24 mm.In another embodiment, the access device can be expanded to provide afirst dimension of about 63 mm, and a second dimension perpendicular tothe first dimension of about 27 mm. These dimensions provide a surgicalspace that is large enough to provide access to at least three adjacentvertebrae without exposing excessive amounts of adjacent tissue that isnot required to be exposed for the procedures being performed. Otherdimensions and configurations are possible that would provide the neededaccess for procedures involving three adjacent vertebrae.

[0134] When the access device is in the second configuration, fixationof the three vertebrae may be performed. As discussed above, fixation isa procedure that involves providing a generally rigid connection betweenat least two vertebrae. Any of the fixation procedures discussed abovecould be used in this method, as could other fixation procedures. Onefixation procedure that could be used is discussed above in connectionwith FIG. 36 wherein the fasteners 600 a, 600 b, and 600 c are advancedthrough the expandable conduit 20 to three adjacent vertebrae and areattached to the vertebrae. The three fasteners 600 a, 600 b, and 600 care interconnected by the elongated member 650. The three fasteners 600a, 600 b, and 600 c and the elongate member 650 comprise a firstfixation assembly. A second fixation assembly may be applied to thepatient on the opposite side of the spine, i.e., about the same locationon the opposite side of the medial line of the spine. Other fixationprocedures could be applied, e.g., including two fasteners that coupledto the L4 and the S1 vertebrae and an elongate member interconnectingthese vertebrae.

[0135] One variation of the first method provides one level of fixationon the anterior side of the patient, e.g., when the fusion device isplaced in the interbody space. For example, fixation of the L5 and S1vertebrae could be provided on the anterior side of the spine, inaddition to the other procedures set forth above (e.g., a two levelpostero-lateral fixation). Also, fixation of the L4 and L5 vertebraecould be provided on the anterior side of the spine, in addition to theother procedures set forth above (e.g., a two level postero-lateralfixation).

[0136] In a second method, substantially the same steps as set forthabove in connection with the first method would be performed. Inaddition, after the access device is inserted, a decompression procedureis performed through the access device. A decompression procedure is onewhere unwanted bone is removed from one or more vertebrae. Unwanted bonecan include stenotic bone growth, which can cause impingement on theexisting nerve roots or spinal cord. Decompression procedures that maybe performed include laminectomy, which is the removal of a portion of alamina(e), and facetectomy, which is the removal of a portion of one ormore facets. In one variation of this method, decompression includesboth a facetectomy and a laminectomy. Any suitable tool may be used toperform decompression. One tool that is particularly useful is akerrison.

[0137] In a third method, substantially the same steps as set forthabove in connection with the first method would be performed. That is,an ALIF procedure is performed in combination with a fixation procedure.In addition, a fusion procedure may be performed through the accessdevice which may have been placed generally posteriorly, e.g.,postero-laterally, tranforaminally or posteriorly, whereby bone growthis promoted between the vertebrae and the fixation assembly, includingat least one of the fasteners 600 a, 600 b, 600 c and/or the elongateelement 650. This procedures is also referred to herein as an “externalfusion” procedure.

[0138] One example of an external fusion procedure that may be performedinvolves placement of a substance through the access device intended toencourage bone growth in and around the fixation assembly. Thus, fusionmay be enhanced by placing a bone growth substance adjacent any of thefasteners 600 a, 600 b, 600 c and/or the elongate member 650. The bonegrowth substance may take any suitable form, e.g., small bone chipstaken from the patient (e.g., autograft), from another donor source(e.g., allograft or xenograft), and orthobiologics.

[0139] After the bone growth substance is applied to the fixationassembly, the access device is removed. Absent the retracting forceprovided by the access device, the patient's tissue generally collapsesonto the bone growth substance. The tissue will thereby maintain theposition of the bone growth substance adjacent to the fixation assembly.The presence of the bone growth substance can cause bone to bridgeacross from the vertebra(e) to one or more components of the fixationassembly.

[0140] In a fourth method, substantially the same steps as set forthabove in connection with the second method would be performed. That is,an ALIF procedure is performed anteriorly, and a decompression procedureand a fixation procedure are performed through the access device whichmay be placed generally posteriorly, e.g., postero-laterally,tranforaminally, or posteriorly. In addition, bone growth substance isplaced in and around a fixation assembly through the access device, asdiscussed above in connection with the third method. The bone growthsubstance encourages bone to bridge across from the vertebrae to thefixation assembly.

[0141] In a fifth method, an ALIF procedure is performed, as discussedabove in connection with the second method. After one or more fusiondevices is placed in the interbody space, access is provided by way ofthe access device, as discussed above, from any suitable anatomicalapproach, e.g., a generally posterior approach. Preferably, apostero-lateral approach is provided. After access has been provided, abone growth substance, such as those discussed above in connection withthe third method, is delivered through the access device. The bonegrowth substance is placed adjacent an interbody space, e.g., the spacebetween the L4 and the L5 vertebrae and/or between the L5 and the S1vertebrae. The bone growth substance encourages fusion of the adjacentvertebrae, e.g., L4 to L5 and/or L5 to S1, by stimulating or enhancingthe growth of bone between adjacent vertebrae, as discussed above.

[0142] In a sixth method, substantially the same steps described inconnection with the first method are performed, except that the fixationprocedure is optional. In one variation of the sixth method, thefixation procedure is not performed. However, after the access device isinserted, a bone growth substance is placed in and around one or moreinterbody spaces through the access device. Where the sixth methodinvolves a two level procedure, the bone growth substance can be placedadjacent the interbody space between the L4 and the L5 vertebra and/orbetween the L5 and the S1 vertebra. Thus, bone growth may occur in theinterbody space and adjacent the interbody space between the vertebrae.

[0143] The foregoing discussion illustrates that an ALEF procedure canbe combined with a variety of procedures that can be performed throughan access device disclosed herein. In addition, though not expressly setforth herein, any combination of the procedures discussed above, and anyother suitable known procedure, may also be combined and performedthrough the access devices described herein, as should be understood byone skilled in the art.

[0144] B. Spine Procedures Providing Minimally Invasive Lumbar InterbodyFusion

[0145] Another category of procedures that may be performed with theaccess devices and systems described above involves a minimally invasivelumbar interbody fusion (referred to herein as a “MILIF”). MILIFprocedures are particularly advantageous because they permit the surgeonto perform a wide variety of therapeutic procedures without requiringfusion by way of an anterior approach, as is required in an ALIF. Thisprovides a first advantage of allowing the surgeon to perform allprocedures from the same side of the patient and also possibly from thesame approach. Also, the access devices and systems disclosed hereinprovide the further advantage of enabling two level procedures, and manyother related procedures, to be performed by way of a singlepercutaneous access. These and other advantages are explained more fullybelow.

[0146] In a first MILIF method, a two level postero-lateral fixation ofthe spine involving three adjacent vertebrae, such as the L4, L5, and S1vertebrae, is provided. Analogous one level procedures and two levelprocedures involving any other three vertebrae also may be provided. Inaddition, the access devices and systems described herein could be usedor modified to accommodate other multi-level procedures, such as a threelevel procedure. The surgeon inserts an access device such as describedherein to a surgical location near the spine. As discussed above, theaccess devices are capable of a wide variety of anatomical approaches.In this procedure, a postero-lateral approach is preferred. Once theaccess device is inserted to a location adjacent the spine, as discussedabove, it may be configured, e.g., expanded, as discussed above, to aconfiguration wherein sufficient access is provided to the surgicallocation.

[0147] Any suitable fusion process may then be performed. For example,an implant may advanced through the access device into the interbodyspace in order to maintain disc height and allow bone growth therein,e.g. as in a fusion procedure. In order to ease insertion of theimplant, it may be beneficial to prepare the interbody space. Interbodyspace preparation may involve removal of tissue or adjusting the heightof the interbody space through the access device, such as in adistraction procedure. Once the interbody space is prepared, a suitableimplant may be advanced through the access device into the interbodyspace, taking care to protect surrounding tissues. Various embodimentsof implants and techniques and tools for their insertion are describedin U.S. application Ser. No. 10/280,489, incorporated by referencehereinabove. In general, the implant preferably is an allograft strutthat is configured to maintain disc height and allow bone growth in theinterbody space.

[0148] In addition to providing a suitable fusion, the first methodprovides fixation of the vertebrae. The fixation procedure may take anysuitable form, e.g., any of the fixation procedures similar to thosedisclosed above. In particular, when the access device is in theexpanded or enlarged configuration, fixation of the three adjacentvertebrae may be performed. One fixation procedure that could be used isdiscussed above in connection with FIG. 36 wherein the fasteners 600 a,600 b, and 600 c are advanced through the expandable conduit 20 to threeadjacent vertebrae and are attached to the vertebrae. The threefasteners 600 a, 600 b, and 600 c are interconnected by way of theelongated member 650. As discussed above, a second fixation assembly maybe applied to the patient on the opposite side of the spine, e.g., aboutthe same location on the opposite side of the medial line of the spine.

[0149] In a second MELIF method, substantially the same procedures setforth above in connection with the first MILIF method are performed. Inaddition, a suitable decompression procedure may be performed, asneeded. As discussed above, decompression involves removal of unwantedbone by way of a suitable decompression technique that may be performedthrough the access device. In one embodiment, decompression is performedthrough the access device after the access device has been expanded. Asdiscussed above, suitable decompression techniques include alaminectomy, a facetectomy, or any other similar procedure.Decompression for the L4, the L5, and/or the S1 vertebrae may be neededand can be performed through the access devices described herein withoutrequiring the access device to be moved from one position to another.

[0150] In a third MILIF method, substantially the same procedures setforth above in connection with the first MILIF method are performed. Inaddition, a further fusion procedure, e.g., a fusion procedure externalto the interbody space, is provided. The external fusion procedure isperformed adjacent to the interbody space wherein bone growth may bepromoted in the proximity of the fixation assembly, e.g., above thepostero-lateral boney elements of the spine, such as the facet jointsand the transverse processes. In one embodiment, when the fixationassembly comprising the fasteners 600 a, 600 b, 600 c and/or theelongate element 650 has been applied to three adjacent vertebrae, asubstance is applied through the access device to one or more componentsof the fixation assembly to maintain or enhance the formation and/orgrowth of bone in the proximity of the fixation assembly. For example, abone growth substance may be placed adjacent any of the fasteners 600 a,600 b, 600 c and/or the elongate member 650. Bone growth substance maytake any suitable form, e.g., small bone chips taken from the patient(e.g., autograft), from another donor source (e.g., allograft orxenograft), and orthobiologics.

[0151] After the bone growth substance is applied to the fixationassembly, the access device is removed. Absent the retracting forceprovided by the access device, the patient's tissue generally collapsesonto the bone growth substance. The tissue will thereby maintain theposition of the bone growth substance adjacent to the fixation assembly.The presence of the bone growth substance advantageously causes bone togrow between the vertebrae and the fixation assembly to form a bridgetherebetween.

[0152] A fourth MILIF method involves substantially the same proceduresperformed in connection with the third MILIF method. In particular, oneor more implants are positioned in the interbody spaces through anaccess device, a fixation procedure is performed through the accessdevice, and a further fusion procedure is performed wherein bone growthsubstance is positioned adjacent the interbody space through the accessdevice. In addition, a decompression procedure is performed through theaccess device that may include a facetectomy and/or a laminectomy.

[0153] A fifth MILIF method involves substantially the same proceduresperformed in connection with the first MILIF method, except that thefixation is optional. In one embodiment, the fixation is not performed.In addition, a further fusion procedure is performed through the accessdevice wherein bone growth substance is positioned adjacent theinterbody space, as discussed above.

[0154] A sixth MILIF method is substantially the same as the fifth MILIFmethod, except that a further fusion procedure is performed through theaccess device. In particular, an implant is positioned in the interbodyspace through an access device, a decompression procedure is performedthrough the access device, and a further fusion procedure is performedwhereby bone growth substance is placed adjacent the interbody spacethrough the access device. As discussed above, the decompressionprocedure may include a facetectomy, a laminectomy, and any othersuitable procedure. As with any of the methods described herein, theprocedures that make up the sixth MILIF method may be performed in anysuitable order. Preferably the decompression procedure is performedbefore the external fusion procedure.

[0155] The foregoing discussion illustrates that a MILIF procedure caninclude a variety of procedures that can be performed through an accessdevice described herein. In addition, though not expressly set forthherein, any combination of the procedures discussed above, and any othersuitable known procedures, may also be combined, as should be understoodby one skilled in the art.

[0156] C. Other Multi-level Procedures

[0157] While the foregoing procedures have involved interbody fusion,the access devices and systems described herein can be employed in avariety of single level and multi-level procedures (e.g., more than twolevels) that do not involve an interbody fusion. For example, adiscectomy can be performed through the access devices described hereinwithout implanting an interbody fusion device thereafter, e.g., toremove a hemeation. In another embodiment, a discectomy can be performedin more than one interbody space without inserting an interbody fusiondevice into each interbody space, e.g., to remove multiple herneations.In another embodiment, a single or multi-level decompression procedurecan be performed to remove unwanted bone growth.

[0158] It will be understood that the foregoing is only illustrative ofthe principles of the invention, and that various modifications,alterations, and combinations can be made by those skilled in the artwithout departing from the scope and spirit of the invention.

What is claimed is:
 1. A method of treating a spine of a patient,comprising: implanting a fusion device via an anterior approach in aninterbody space between at least two of a first vertebra, a secondvertebra and a third vertebra; inserting an access device into saidpatient with said access device in a first configuration having a firstcross-sectional area at a distal portion thereof; actuating said accessdevice to a second configuration having an enlarged cross-sectional areaat said distal portion thereof such that the distal portion extendsacross at least a portion of each of the three adjacent vertebrae; andperforming a multi-level procedure through the access device across theat least three adjacent vertebrae.
 2. The method of claim 1, wherein themulti-level procedure is a two-level procedure.
 3. The method of claim1, wherein the access device is inserted via a postero-lateral approach.4. The method of claim 1, wherein the access device is inserted via atransforaminal approach.
 5. The method of claim 1, wherein the accessdevice is inserted via a posterior approach.
 6. The method of claim 1,wherein the multi-level procedure is fixation.
 7. The method of claim 6,further comprising performing a fixation procedure via an anteriorapproach.
 8. The method of claim 6, further comprising performing afusion procedure external to the interbody space through the accessdevice after performing fixation.
 9. The method of claim 6, furthercomprising performing decompression through the access device prior toperforming fixation.
 10. The method of claim 9, further comprisingperforming a fusion procedure external to the interbody space throughthe access device after performing fixation.
 11. The method of claim 1,wherein the multi-level procedure comprises delivering a bone growthsubstance through the access device.
 12. The method of claim 11, furthercomprising performing decompression through the access device beforedelivering the bone growth substance through the access device.
 13. Themethod of claim 11, further comprising performing decompression throughthe access device after delivering the bone growth substance through theaccess device.
 14. A method of treating a spine of a patient,comprising: anteriorly exposing an interbody space between at least twoof a first vertebra, a second vertebra, and a third vertebra; placing afusion device in the interbody space; inserting an access device throughan incision in the skin of the patient generally posteriorly until adistal portion thereof is located adjacent the spine, said access devicebeing inserted in a first configuration having a first cross-sectionalarea at the distal portion thereof, actuating said access device to asecond configuration having an enlarged cross-sectional area at saiddistal portion thereof; providing a first fastener configured forinsertion into said patient through said access device and forattachment to the first vertebra; providing a second fastener configuredfor insertion into the patient through said access device and forattachment to a second vertebra; providing a third fastener configuredfor insertion into said internal passage of said expandable conduit andfor attachment to a third vertebra; attaching said first, second, andthird fasteners to said first, second, and third vertebrae; inserting anelongated member through said access device and moving said elongatedmember adjacent to said first, second, and third fasteners; and securingsaid elongate member to said first, second, and third fasteners.
 15. Amethod of treating the spine of a patient, comprising: anteriorlyexposing an interbody space between at least two of a first vertebra, asecond vertebra, and a third vertebra; placing a fusion device in theinterbody space; inserting an access device through an incision in theskin of the patient generally posteriorly until a distal portion of theaccess device is located adjacent the spine of the patient, said accessdevice being inserted in a first configuration having a firstcross-sectional area at the distal portion thereof; actuating saidaccess device to a second configuration having an enlargedcross-sectional area at said distal portion thereof; advancing adecompression tool through the access device; removing a portion of bonefrom at least one of the first, second, and third vertebrae through theaccess device; providing a first fastener configured for insertion intosaid patient through said access device and for attachment to the firstvertebra; providing a second fastener configured for insertion into thepatient through said access device and for attachment to a secondvertebra; providing a third fastener configured for insertion into saidinternal passage of said expandable conduit and for attachment to athird vertebra; attaching said first, second, and third fasteners tosaid first, second, and third vertebrae; inserting an elongated memberthrough said access device and moving said elongated member adjacent tosaid first, second, and third fasteners; and securing said elongatemember to said first, second, and third fasteners.
 16. The method ofclaims 15, further comprising placing a bone growth substance throughthe access device and adjacent at least one of said first, second, andthird fasteners and said elongate member to enhance bone growth.
 17. Amethod of treating a spine of a patient, comprising: anteriorly exposingan interbody space between at least two of a first vertebra, a secondvertebra, and a third vertebra; placing a fusion device in the interbodyspace; inserting an access device through an incision in the skin of thepatient generally posteriorly until a distal portion of the accessdevice is located adjacent the spine of the patient, said access devicebeing inserted in a first configuration having a first cross-sectionalarea at the distal portion thereof; actuating said access device to asecond configuration having an enlarged cross-sectional area at saiddistal portion thereof; providing a first fastener configured forinsertion into said patient through said access device and forattachment to the first vertebra; providing a second fastener configuredfor insertion into the patient through said access device and forattachment to a second vertebra; providing a third fastener configuredfor insertion into said internal passage of said expandable conduit andfor attachment to a third vertebra; attaching said first, second, andthird fasteners to said first, second, and third vertebrae; inserting anelongated member through said access device and moving said elongatedmember adjacent to said first, second, and third fasteners; and securingsaid elongate member to said first, second, and third fasteners; andplacing a bone growth substance through the access device and adjacentat least one of said first, second, and third fasteners and saidelongate member to enhance bone growth.
 18. A method of treating a spineof a patient, comprising: anteriorly exposing an interbody space betweenat least two of a first vertebra, a second vertebra, and a thirdvertebra; placing a fusion device in the interbody space; inserting anaccess device through an incision in the skin of the patient generallyposteriorly until a distal portion of the access device is locatedadjacent the spine of the patient, said access device being inserted ina first configuration having a first cross-sectional area at the distalportion thereof; actuating said access device to a second configurationhaving an enlarged cross-sectional area at said distal portion thereof;and placing a bone growth substance through the access device andadjacent an interbody space defined between at least two of said first,second, and third vertebrae to enhance bone growth therebetween.
 19. Themethod of claim 18, further comprising: advancing a decompression toolthrough the access device; and removing a portion of bone from one ofthe first vertebrae, the second vertebrae, and the third vertebraethrough the access device.
 20. A method of treating the spine of apatient, comprising: inserting an access device through an incision inthe skin of the patient generally posteriorly until a distal portion ofthe access device is located adjacent the spine of the patient, saidaccess device being inserted in a first configuration having a firstcross-sectional area at the distal portion thereof; actuating saidaccess device to a second configuration having an enlargedcross-sectional area at said distal portion thereof that spans at leasta portion of a first vertebra, a second vertebra, and a third vertebra;placing a fusion device through the access device and in at least one ofa first interbody space between the first and second vertebrae and asecond interbody space between the second and third vertebrae;performing a two level fixation procedure spanning the first and secondinterbody spaces through the access device; advancing a decompressiontool through the access device; and removing a portion of bone from oneof the first vertebrae, the second vertebrae, and the third vertebraethrough the access device.
 21. The method of claim 20, wherein theportion of bone removed comprises a portion of a facet.
 22. The methodof claim 20, wherein the portion of bone removed comprises a portion ofa lamina.
 23. The method of claim 20, further comprising placing a bonegrowth substance through the access device and adjacent at least one ofthe first interbody space and the second interbody space to enhance bonegrowth therebetween.
 24. A method of treating a spine of a patient,comprising: inserting an access device through an incision in the skinof the patient generally posteriorly until a distal portion of theaccess device is located adjacent the spine of the patient, said accessdevice being inserted in a first configuration having a firstcross-sectional area at the distal portion thereof; actuating saidaccess device to a second configuration having an enlargedcross-sectional area at said distal portion thereof that spans at leasta portion of a first vertebra, a second vertebra, and a third vertebra;placing a fusion device through the access device and in at least one ofa first interbody space between the first and second vertebrae and asecond interbody space between the second and third vertebrae; andplacing a bone growth substance through the access device and adjacentat least one of the first interbody space and the second interbody spaceto enhance bone growth therebetween.
 25. The method of claim 24, furthercomprising: advancing a decompression tool through the access device;and removing a portion of bone from one of the first vertebrae, thesecond vertebrae, and the third vertebrae through the access device. 26.The method of claim 24, wherein the portion of bone removed comprises aportion of a facet.
 27. The method of claim 24, wherein the portion ofbone removed comprises a portion of a lamina.